Obtaining arthroscopic access into orthopedic joints to perform surgical procedures can be extremely challenging. This is particularly true of the hip joint, which has two tissue barriers that must be crossed in order to gain access to the inner part of the joint. The outer barrier is known as the capsule, a series of tight overlapping ligaments surrounding the joint, effectively sealing off the hip joint from the remainder of the body. The area within the capsule is known as the peripheral compartment.
Within the peripheral compartment, the joint is fluidly sealed by a skirt-like tissue known as the labrum which is attached to the acetabular rim and hugs tightly around the base of the femoral head. The labrum/femoral head interface creates a vacuum seal within the joint which helps to hold the femoral head tightly within the acetabulum. In order to gain access to the central compartment (i.e., the portion of the joint within the labrum lying between the femoral head and acetabulum) the seal of the labrum must be broken and instruments then introduced into the very narrow opening between the bottom edge of the labrum and femoral head.
In arthroscopic surgery, access to the peripheral compartment is typically obtained through the use of elongate tubular devices (e.g., arthroscopic portals or cannulas), which are inserted through the patient's skin and through the ligaments of the capsule to provide a tunnel or lumen through which instruments may be introduced. Multiple access portals are typically employed, with one access portal being used for visualization (e.g., for placement of an arthroscope), and the remaining portal(s) being available for the introduction of other instruments.
However, the creation of access portals can be problematic. For one thing, the patient's anatomy (e.g., bone, blood vessels, nerves, etc.) can greatly restrict the possible portal locations. Furthermore, some hip structures (e.g., the articular cartilage on the femoral head, the articular cartilage on the acetabular cup, etc.) can be quite delicate, thereby requiring great precision when forming the access portal so as to avoid damaging delicate structures. Additionally, some of the intervening tissue (e.g., the joint capsule) can be quite tough, thus requiring substantial force to penetrate the tissue, and thereby raising the danger of accidental plunging as an access tool breaks through the intervening tissue. Such accidental plunging increases the risk of inadvertently damaging delicate joint structures (e.g. articular cartilage).
Due to the numerous difficulties and concerns associated with forming an access portal, surgeons have traditionally resorted to a multi-step procedure for forming the access portal.
More particularly, surgeons have traditionally first passed a small needle (sometimes referred to as an access needle) down to the interior of the hip joint. This is generally done by first using external anatomical landmark and tactile feedback for needle guidance; then, as the sharp tip of access needle enters the capsule of the joint and approaches delicate structures (e.g. articular cartilage), fluoroscopy is used to carefully direct final needle placement. Inexperienced surgeons, or experienced surgeons dealing with particularly problematic cases, may also use fluoroscopy during the earlier stages of needle placement.
Next, a guidewire is placed through the lumen of the access needle, then the access needle is removed. Next, the tissue surrounding the guidewire is opened laterally by passing a series of tissue dilators over the guidewire. These dilators progressively increase in diameter so as to dilate the tissue disposed between the skin and the interior of the joint.
Once the opening from the top surface of the skin down to the interior of the joint has been established, a tubular liner (sometimes referred to as an “access cannula”) is inserted over the guidewire, and the guidewire may be withdrawn from the joint. This access cannula holds the incision open and provides a surgical pathway (or “corridor”) from the top surface of the skin down to the interior of the hip joint, thereby enabling instrumentation (e.g., arthroscopes, surgical instruments, etc.) to be passed through the central lumen of the access cannula so as to reach the remote surgical site within the joint.
This multi-step process requires substantial effort on the part of the surgeon, increases the instrumentation necessary for the procedure, and extends the duration of the procedure.
Surgeons have also created portals by inserting long spinal needles into the joint under fluoroscopic guidance. In order to avoid damaging the cartilage of the hip joint with the needle, the femur is distracted from the pelvis by approximately 5 to 10 millimeters to create a gap between the femoral head and the acetabulum of the pelvis. The needle is accordingly guided into the gap.
Hip distraction typically requires the use a distraction table, a surgical table that includes a post placed against the patient's perineum and a tensioning device which fastens to the patient's foot or ankle and allows high forces (e.g., 50 to 70 pounds) to be exerted on the patient's leg to distract the femur and create space within the joint. These tables not only are large, cumbersome and expensive, but they limit the mobility of the joint during the procedure and frequently produce complications such as nerve damage.
Even with use of a distraction table, damage to the cartilage and other joint tissue may be difficult to avoid. The capsule surrounding the hip joint is significantly denser and “tougher” than tissue externally surrounding the capsule. Accordingly, a high amount of force is required to pierce the capsule, even with use of a sharp needle. However, the capsule is relatively thin, 2 to 15 millimeters, and the high amount of force required to pierce it can inadvertently cause a needle to uncontrollably “pop” through the capsule and damage tissue beyond. The space within the peripheral compartment is also relatively small for use with arthroscopic devices. Accordingly, several portals must be created to enable proper access to the joint. Each time a portal is created, the risk of unintended harm is increased.
Methods and devices have been proposed for accessing the hip joint without using a distraction table. For example, commonly assigned U.S. patent application Ser. No. 12/483,446, filed Jun. 12, 2009, entitled “Methods and Apparatus for Joint Distraction”, the entirety of which is incorporated by reference herein, discloses various internal distraction devices for distracting the hip and other joints. These devices use balloons or other expandable features placed within the central compartment to displace the femoral head further away from the acetabulum in order to allow access for surgical instruments. While such devices eliminate the need for a distraction table, challenges may still be encountered in introducing these devices into the peripheral and central compartments. Further, even where a conventional distraction table is used, the placement of portals and the introduction of instruments into the peripheral and central compartments remain challenging.
On account of the foregoing, there is a substantial need for a simpler, faster and more convenient approach for creating an access portal to the interior of the hip joint.
More particularly, there is a substantial need for a new approach for deploying an access cannula into the interior of the hip joint.
There is also a substantial need for locking an access cannula so that its distal tip is constrained within the capsule of the hip joint so as to facilitate the insertion and removal of instruments.
In addition to the foregoing, there is also a significant need for creating additional workspace once access is gained to the interior of the hip joint, whereby to afford surgeons improved visualization at the surgical site and more room to maneuver.